Nebulizers can be used to deliver medications which are inhaled as an aerosol laden with the medicine over a delivery time of about 20 to 30 minutes. The use of nebulizers is found in the treatment of asthma or bronchitis or other respiratory related diseases. An attending respiratory technician, medical assistant or physician is required to insure the dosage is properly inhaled.
The length of time to administer the medications is quite long and therefore costly as well as uncomfortable for the patient.
Aerosol mist production makes use of an ultrasonic nebulizer to produce an aerosol mist for creating a humid environment and delivering drugs to the lungs.
Ultrasonic nebulizers function by transmitting ultrasound waves of sufficient energy through a liquid, the waves being directed at an air-liquid interface of the liquid from a point underneath or within the liquid. Liquid particles are ejected from the surface of the liquid into the surrounding air following the disintegration of capillary waves produced by the ultrasound. This technique can produce a very fine mist.
Aerosol mists produced by ultrasound are preferred because a heating element is not required to generate water vapor or mist and a smaller particle size of the aerosol can be obtained with the ultrasonic waves.
Most of the ultrasonic nebulizers currently in use today provide medications that are in a liquid form or a colloidal liquid suspension of particles. U.S. Pat. No. 4,094,317 patent entitled “Nebulizer System”; U.S. Pat. No. 5,551,416 “Nebulizer and Nebulizer Control System” and US 2005/0081845 A1 entitled “Breath Enhanced Ultrasonic Nebulizer and Dedicated Dose Ampoule” are examples of such devices.
US 2003/0015195 A1 published on Jan. 3, 2003; entitled “Powder Formulation Distinguishing Systems and Method for Dry Powder Inhalers” and US 2005/0123483 show inhaler type devices.
Dr. Raghuprasad, the inventor of a “Mist Inhaler” described in U.S. Pat. No. 5,186,164 discussed a novel way to generate a vapor which is condensed by a powder containing medications into a cloud of very fine particles that can be inhaled deep into a patient's lungs. As described the inhaler includes an enclosure, preferably a transparent container, which enables the patient to observe the formation of the cloud. The cloud is formed because of the provision within the enclosure of the proper pressure, moisture content, temperature, and a dust-like powder that is actually the medication and which seeds the cloud. A heater is placed adjacent to a liquid to cause the liquid to heat and vaporize. A small pump reduces the pressure within the container only the amount required to achieve the proper conditions for the cloud formation. A liquid is placed in a liquid containing part of the container. The patient actuates the starting mechanism and the pump partially evacuates the transparent container; then the heating element commences vaporizing the water, after which suitable medication powder flows into the transparent container, and seeds the cloud. The cloud should form at the instant the powdered medication is introduced into the transparent container. This is the signal for the patient to inhale the cloud.
This prior art device, while effective as an inhaler, did require a heater to be placed adjacent to the liquid to heat and vaporize the liquid. This pre-heating involves a small time delay and adds to the complexity of the inhaler as an additional cooling coil is required.
Accordingly it is desirable to provide a rapid responding nebulizer device that needs no heater, but can still accomplish a dispersion of dry powder medications or even oil soluble medicines in a very rapid manner.
It is further desirable to enable the patient to inhale all of the medication in as short as one or two breaths rather than the several minutes, typically 20 to 30 minutes required of currently available nebulizers.
These beneficial features are provided in the device of the present invention described as follows.